Evidence from epidemiological and experimental studies emphasize the significance of dietary salt intake in the development of hypertension. Several lines of evidence indicate that young animals are especially sensitive to excess sodium chloride intake. Because it has been repeatedly demonstrated that exogenous factors can have a prepotent effect on the organization of physiological systems if they are presented around the perinatal period, it is reasonable to suspect that inappropriately high sodium chloride intake in the neonate might have inordinate, deleterious effects on cardiovascular development. Unfortunately, systematic studies of the effects of salt intake on cardiovascular control systems during the immediate postnostal period have not been performed. One reason for this is that it has been difficult to manipulate sodium intake in a controlled manner in offspring that normally receive mother's milk as the total source of nutrition. Recently, a technique of infant feeding for the rat has been perfected. Neonatal animals are reared in a controlled environment without the present of a dam. The application of this technique has thus far been primarily to investigate brain and behavioral development. However, the method is ideally suited to investigate the long-term cardiovascular effects of altered dietary substances, such as sodium, during the neonatal period. The present proposal will use the artificial rearing technique to manipulate salt levels in the diet of neonates. Normotensive, genetically borderline hypertensive, spontaneously hypertensive, and renal compromised rats exposed to early salt feeding will subsequently be studied as juveniles (at the time of weaning) and as adults to evaluate the effects of such treatment on the sympathetic contribution to cardiovascular control. The results of these experiments will provide essential new information about the effects of early dietary sodium in the development of cardiovascular function.